CDs, DVDs and Blu-ray Discs
DIC's coating materials are used to protect the surface of CDs and other optical discs.
Look carefully the next time you take out a CD
Optical discs such as CDs, DVDs and Blu-ray Discs can record massive amounts of data and store it for an extended period. However, this is only possible if the surface of the disc is protected properly. DIC technologies play an essential role here. Protective surface coatings for optical discs are a DIC specialty.
Small scratches, stains or bits of dust can cause read errors. To prevent scratches and stains, a hard coating is applied to the surface.
Hard coating is necessary to make disc surfaces resistant to scratches. A smooth, low-friction coating also makes it easy to wipe off dust and oil-based stains, such as fingerprints. Accordingly, manufacturers seek coating materials that deliver superb hardness and a high degree of smoothness, thus ensuring stable recording and long-term storage capabilities.
Cures instantly and resists deforming
DIC coating materials use UV-curable resins that harden from a liquid state in seconds when irradiated with UV light. Because these resins are light sensitive, meaning they require only a small amount of UV light to cure—which shortens processing times—they are well suited to mass production applications.
The harder resin becomes, the more resistant it will be to scratches, but excessive hardening will result in volumetric shrinkage, which may cause the disc to warp. Warped discs are difficult to insert smoothly into disc drives and trigger playback errors. For this reason, DIC has developed UV-curable resins that deliver outstanding hardness with minimal volumetric shrinkage.
Moving forward to respond to evolving needs
Because labels are often printed directly onto protective coatings, it is also imperative to respond to the need for a high level of transparency. However, one problem with most highly transparent protective coating materials is that they tend to yellow under fluorescent and other indoor lighting. DIC's UV-curable resins boast superb transparency and resistance to yellowing. DIC has also developed a proprietary process for treating these resins that minimizes deterioration of the recording layer due to high heat and humidity, thereby ensuring excellent durability.
DIC's UV-cured resins are used not only to protect the surface of optical discs but also as an adhesive for laminating DVDs. DIC also expects to see increased use on Blu-ray Discs. Looking ahead, DIC will continue working to establish a leading position for itself in the area of electronics and information materials.